1. Field of the Invention
The invention is directed to an x-ray diagnostics installation of the type having a high-voltage generator for an x-ray tube for generating an x-ray beam, a detector arranged in the x-ray beam for acquiring the x-ray dose, a control unit supplied with a signal from the detector for controlling the high-voltage generator and an image converter.
2. Description of the Prior Art
German OS 21 35 205 discloses an x-ray diagnostics installation having an automatic exposure unit, whereby a characteristic representative of the ongoing x-ray dose is acquired during the emission of x-rays. The ongoing radiation can thereby be switched off after a prescribed dose value has been reached.
In such x-ray diagnostics installations having an x-ray image intensifier, it is known to arrange an air-filled ionization chamber in front of the x-ray image intensifier as an auxiliary component. The slight current between two electrode plates with a voltage thereacross is directly proportional to the incident, ionizing radiation. The dose is determined by integration. The measuring precision, however, is insufficient for fluoroscopic doses.
In an x-ray image converter, for example an a-Si:H x-ray image detector, the image information is only available some time after the end of the x-ray pulse because the image detector is fundamentally operated in a storing mode. A dose measurement is thus not possible during the current x-ray pulse but only some time after the end thereof.